Three of the features to focus on when considering a visco foam mattress are density, firmness, and temperature (of both your room and yourself). These are some of the factors that effect not only your nightly sleeping comfort but also the longevity of your mattress. Memory foam mattresses are one type of visco foam mattresses.
Visco elastic was originally developed for NASA to relieve pressure felt by astronauts during take-off, but its most common use today is as a visco foam (or memory foam) mattresses. Since the visco elastic foam is too soft to make an entire bed, it is often layered over a firmer core mattress and acts as a topper. Visco elastic is five times denser than regular foams and since it’s temperature sensitive, it molds itself to the body’s shape in reaction to natural temperature fluctuations of the body. They key to a good visco foam mattress is its density, firmness and heat responsiveness.
A high density visco foam mattress contains billions of small, tightly packed open cells that allow air to flow slowly between the cells. Generally, the higher the density of the visco foam mattress, the greater the comfort and support. High density visco foam slowly takes on the shape of your body, and evenly distributes your weight and relieves pressure points. Visco foam has “memory”, which means that it will regains its original shape when you move. The longer it takes the visco foam mattress to recover from a compressed state, the more supportive the mattress. Not surprisingly, high density visco foam mattresses are more expensive than other foam mattresses. To attain the high density quality of visco elastic foam, greater amounts of costly resin is combined with air in the manufacturing process.
In contrast, a lower density visco foam mattress has bigger but fewer open cells, and does not regain its original shape as readily. The air is spread to other cells much faster, and your body is not supported as well. Since the cells are larger and less dense, the cell structure will lose its integrity faster and the mattress will show sagging in the middle of you bed very quickly.
The firmness or softness of a visco foam mattress is not determined by the density of the visco foam, but rather by the ILD/IFD (Indentation Load Deflection, Indentation Force Deflection) rating. The ILD/IFD measures ability of the visco foam to push back against force, and the higher the rating, the firmer the feel of the visco foam. The ILD/IFD rating ranges from an extremely soft 10 to a semi-rigid 120. Finding the right rating for your taste is important because while a lower rated material may conform better to your body and more evenly distributes weight, too low a rating leads to inadequate support.
High quality visco memory foam changes its firmness rating based on the temperature of your body. At cooler temperatures, visco foam feels firmer and offers more support. At warmer temperatures, visco foam feels softer and offers more comfort as it contours your body. Temperature-sensitive visco foam is a key element to your sleeping comfort; memory foam mattresses without this feature should be avoided.
Memory foam mattresses and toppers can dramatically improve the quality of your sleep and may be right for you. However, before you invest in memory foam, make sure to select a high density, temperature-sensitive visco elastic that will give you the support and comfort you need for years to come.